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Infect. Immun., 03 1995, 926-933, Vol 63, No. 3
X Jiang, SH Gregory and EJ Wing
Previous findings in our laboratory indicated that the bulk of Listeria
monocytogenes injected intravenously into mice and recovered in the liver
is taken up and replicates within hepatocytes. Other investigators have
shown that hepatocytes can display costimulatory adhesion molecules,
express major histocompatibility complex class I and II molecules, and
secrete a number of cytokines, including interleukin-1 (IL-1), IL-6, and
IL-8. These data suggest that hepatocytes may serve as accessory cells in
the immune response to L. monocytogenes. The accessory function and
capacity of hepatocytes to present listerial antigens, however, have never
been explored. We undertook a series of experiments to examine the response
of Listeria- immune T lymphocytes to murine hepatocytes preincubated with
heat- killed listeriae (HKL). Electron micrographs showing the organism
within membrane-limiting vacuoles demonstrated the capacity of hepatocytes
to internalize HKL. T cells cocultured with hepatocytes pulsed with HKL
exhibited a 5- to 10-fold increase in [methyl- 3H]thymidine incorporation
relative to T cells cultured with either hepatocytes or HKL alone.
Similarly, gamma interferon production by immune T cells was elevated
significantly in cultures that contained both hepatocytes and HKL. The
optimal response of T cells required lysosomal processing of HKL by
hepatocytes and contact between the two cell populations. Furthermore,
maximum T-cell proliferation and gamma interferon production were dependent
upon the presence of CD4+ T lymphocytes and the expression of Ia antigens.
Taken together, these findings demonstrate that hepatocytes pulsed with HKL
can stimulate the antigen-specific response of immune T lymphocytes. These
results suggest that hepatocytes can serve as accessory cells in host
defenses to listerial infections of the liver.
Copyright © 1995, American Society for Microbiology
Hepatocytes can serve as accessory cells in the response of immune T lymphocytes to heat-killed Listeria monocytogenes
Department of Medicine, University of Pittsburgh Medical Center, Montefiore University Hospital, Pennsylvania 15213-2582.
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